Snowmobile drive train

Abstract

A snowmobile drive train employing a drive belt and an endless track is provided. The snowmobile comprises an engine including an output shaft, with a support member located adjacent to the engine. A drive pulley and a driven pulley are mounted on the support member so that the drive belt can be removed from the snowmobile by passing the drive belt over the pulleys. An isolation member couples the engine output shaft to the driven pulley, and the support member maintains the drive and driven pulleys in a constant positional relationship relative to each other. The support member also includes reduction gears for driving the endless track.

Description

FIELD OF THE INVENTION[0001] The present invention generally relates to snowmobiles. More particularly, the invention concerns a snowmobile with an improved drive train.BACKGROUND OF THE INVENTION[0002] A drive train is the transmission system that connects a vehicle's engine output shaft to the vehicle drive axle or axles. For example, automobile drive trains may include a transmission, drive shaft, and drive axles. Snowmobile drive trains generally include a variable ratio belt drive system having a driving pulley that is directly coupled to the engine output shaft. The driving pulley usually includes a centrifugal clutch through which the drive ratio of the belt drive varies as a function of engine speed and torque. The drive belt connects the drive pulley to a driven pulley that is coupled to a jack shaft which in turn drives a chain and sprocket reduction drive. The reduction drive is coupled to an axle that drives sprocket wheels, which turn an endless track. This arrangement ...

AI Technical Summary

Benefits of technology

[0008] The present invention alleviates to a great extent the disadvantages of conventional snowmobile drive trains by providing a drive train system that maintains the drive and driven pulleys in a fixed relationship relative to each other, while allowing the drive belt to be easily removed from the pulleys.

[0009] In a preferred embodiment, a support member is located adjacent to the snowmobile engine. The drive pulley and driven pulley are rotatably mounted to the support member, with the drive belt looped around the pulleys, the pulleys mounted on the support member so that the drive belt can be removed from the snowmobile by passing the drive belt over the pulleys. The support member maintains the two pulleys in a precise alignment, greatly extending the operating life of the drive belt and simultaneously increasing drive train efficiency.

[0010] An isolation member couples the drive pulley to the engine output shaft, thereby permitting the engine to move relative to the support member, so that operator comfort is maintained.

[0011] According to one aspect of the present invention, the support member may include two gears for coupling the driven pulley to the endless track. The gears decrease the weight and complexity of the drive train, while increasing efficiency.

[0012] According to another aspect of the present invention, the support member is constructed to absorb heat generated by the engine, thereby minimizing heat transfer to the pulleys. By decreasing engine heat transfer to the pulleys, the operating life of the drive belt is substantially increased.

[0013] In yet another aspect of the present invention, a housing is structured to encompass the pulleys and drive belt, increasing ascetics of the snowmobile, and protecting the pulleys and drive belt from the environment.

Problems solved by technology

This arrangement suffers a number of drawbacks, one of which is that the engine heat, vibrations and movements are directly translated to the driving pulley.

Therefore, with the engine mounted on flexible rubber supports, the position and alignment of the drive pulley relative to the driven pulley varies constantly during snowmobile operations, decreasing drive train efficiency.

Moreover, the misalignment between the two pulleys causes heat to build up in the drive belt, decreasing the operating life of the drive belt.

And, because the pulleys are generally made of aluminum, which has a high thermal conductivity, heat from the engine output shaft is transferred to the drive pulley, which heats the drive belt even more, further decreasing operating life.

Efforts to minimize engine movement by removing the isolators and directly attaching the engine to the frame have generally been unsuccessful because the engine vibration is transmitted to the frame, detrimentally affecting operator comfort, and increasing fatigue failure of snowmobile components attached to the frame.

Moreover, the extra weight of the jack shaft and related components increases the overall snowmobile weight, further decreasing efficiency and performance.

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